Alternator:

[Rob]

Does anyone know what series of Delco alternator may be on my truck? 1977 R795 with an ENDT 865B engine. There are no tags anyplace on the unit. It is an internal regulator type alternator.

I plan to pull it off tonight and take it apart. The regulator does not cut in, or pick up until the engine is revved to about 1250rpm. It then will start to charge but only after the engine is held at a high idle for about five seconds. It then appears to work properly.

Thanks,

Rob

[theakerstwo]

Does anyone know what series of Delco alternator may be on my truck? 1977 R795 with an ENDT 865B engine. There are no tags anyplace on the unit. It is an internal regulator type alternator.

I plan to pull it off tonight and take it apart. The regulator does not cut in, or pick up until the engine is revved to about 1250rpm. It then will start to charge but only after the engine is held at a high idle for about five seconds. It then appears to work properly.

Thanks,

Rob

I dont know which one but the slow charge responce is not un common.

[Rob]

I dont know which one but the slow charge responce is not un common.

Hi Glenn, I've seen this problem before also, but they usually will pick up eventually. This one will not. Repeated starts of the engine and not revving it up results in a dead set of batteries.

Looking at the size I think it is a 25SI series but I'm not sure.

Rob

[HK Trucking]

Does anyone know what series of Delco alternator may be on my truck? 1977 R795 with an ENDT 865B engine. There are no tags anyplace on the unit. It is an internal regulator type alternator.

I plan to pull it off tonight and take it apart. The regulator does not cut in, or pick up until the engine is revved to about 1250rpm. It then will start to charge but only after the engine is held at a high idle for about five seconds. It then appears to work properly.

Thanks,

Rob

The late model Internationals at work with Delco alternators do that too.

The old Leece Neville alternators did that.

I'd always just bring the RPM's up gently to the point where the voltmeter "spiked" up to 14 volts, then it would keep charging after that even at idle.

[Rob]

The late model Internationals at work with Delco alternators do that too.

The old Leece Neville alternators did that.

I'd always just bring the RPM's up gently to the point where the voltmeter "spiked" up to 14 volts, then it would keep charging after that even at idle.

Hi Herb, I have to hold the idle up there for nine to ten seconds before it will hold and not drop. Otherwise, it reverts to about 10-11 volts on the gauge. I verified the output with a calibrated meter and the dash gauge is within 2 percent of accurate, (rounded to the hundreth place).

Rob

[jerrymac]

It's not uncommon to have to 'excite' an older style alternator before it begins to charge, but ten seconds seems a

little excessive. You might just want to update to a newer style alternator that doesn't need to be 'excited' any more

to charge. Otherwise, if you have a complete VIN, I can probably get one of our parts guys to look it up and tell you

what alternator came on your truck originally , if Volvo will still give them access to 1977 R Model parts.

Since Volvo bought Mack, it is getting really hard for our guys to look up parts for older Macks. Since Volvo trucks

don't last more than 4 years before going to the bonepile, they can't seem to understand why people would be looking

for parts for 30 year old Macks. Volvo has fixed that now though, as they now guarantee that no Mack built after

January 2007 will last more than 4 years either.

[HK Trucking]

Volvo has fixed that now though, as they now guarantee that no Mack built after

January 2007 will last more than 4 years either.

[Rob]

It's not uncommon to have to 'excite' an older style alternator before it begins to charge, but ten seconds seems a

little excessive. You might just want to update to a newer style alternator that doesn't need to be 'excited' any more

to charge. Otherwise, if you have a complete VIN, I can probably get one of our parts guys to look it up and tell you

what alternator came on your truck originally , if Volvo will still give them access to 1977 R Model parts.

Since Volvo bought Mack, it is getting really hard for our guys to look up parts for older Macks. Since Volvo trucks

don't last more than 4 years before going to the bonepile, they can't seem to understand why people would be looking

for parts for 30 year old Macks. Volvo has fixed that now though, as they now guarantee that no Mack built after

January 2007 will last more than 4 years either.

Hi Jerry & Herb, I figured the exciter, or pmg was getting weak, and was the root of evil here. I don't work on anything this small but wanted to identify the unit so to research and order parts. The V.I.N. of the truck is: R795S5322. The alternator appears to be the same type the truck was built with, but is repainted and probably a replacement to the original.

I don't plan to have a large electrical draw over original with this truck, so upsizing is not a neccessity.

Chances are that with what I seen and read in trade magazines about the Volvo touch to trucking, your above mentioned comments are not far off. As a reference; I have a customer that has not one, but two VNL series Volvo tractors. Both are powered by Caterpillar engines, Rockwell transmissions, Eaton rears, and both have near a million miles on them. Both are former fleet tractors on air. They are "shook apart" due to the abundance of plastic used in them but very reliability mechanically. This owner bought two "new" 2005 models, (I can't remember the series) and they are both gone from his fleet replaced with Internationals. I know that both the 2005 models had Volvo engines and were unreliable with electronics issues. I never see the trucks for mechanical other than air conditioning work. These trucks are used for hauling hogs, cattle, and feed. Nothing that I would call abusive and maintained reasonably well by in-house mechanics.

I like these Volvo trucks A LOT! Both have a natural tendency to smack deer quite often. I've put two hoods, grilles, headlamps, bumpers and soft parts on each! This is in addition to the normal repairs of age.

Rob